If you are using IIS/PHP how interchangeable is that with LAMP? In other words if I develop locally using IIS/Windows can I just drop the same code onto a LAMP server without breaking anything?
I run PHP on Windows but with the full LAMP static (Apache running on Windows) and deploy to Linux without modification. I suspect you could also do that with IIS (as PHP abstracts the server interface) but I have not tried it.
If you hard-code paths in the code that refer to Linux-specific things, it won't work in Windows.
That said, if it works on Windows, it will most likely work on Linux, but a VM should still be favored due to the probability of prod being Linux.